only emit post flush (#782)

* only emit post flush

* fix missing var

* add telamohn test

Author: mafintosh

lib/core.js

@@ -55,6 +55,7 @@ module.exports = class Core {
     this.closed = false
 
     this.hintsChanged = false
+    this.remoteContiguousLengthChanged = false
 
     this._bitfield = null
     this._verifies = null
@@ -86,6 +87,17 @@ module.exports = class Core {
     s._monitorIndex = -1
   }
 
+  emitRemoteContiguousLength() {
+    if (!this.remoteContiguousLengthChanged) return
+    this.remoteContiguousLengthChanged = false
+
+    const length = this.header.hints.remoteContiguousLength
+
+    for (let i = this.monitors.length - 1; i >= 0; i--) {
+      this.monitors[i].emit('remote-contiguous-length', length)
+    }
+  }
+
   emitManifest() {
     for (let i = this.monitors.length - 1; i >= 0; i--) {
       this.monitors[i].emit('manifest')
@@ -819,10 +831,7 @@ module.exports = class Core {
   updateRemoteContiguousLength(length) {
     this.header.hints.remoteContiguousLength = length
     this.hintsChanged = true
-
-    for (let i = this.monitors.length - 1; i >= 0; i--) {
-      this.monitors[i].emit('remote-contiguous-length', length)
-    }
+    this.remoteContiguousLengthChanged = true
   }
 
   onappend(tree, bitfield) {

lib/replicator.js

@@ -1434,6 +1434,8 @@ class Peer {
 
     if (this.core.hintsChanged) await this.core.flushHints()
     if (drop === false) this._update()
+
+    this.core.emitRemoteContiguousLength()
   }
 
   onreorghint() {

test/snapshots.js

@@ -262,3 +262,19 @@ test('error when using inconsistent snapshot', async function (t) {
   await snapshot.close()
   await core.close()
 })
+
+test('snapshot works with an active atomized session without persisted dependency state', async function (t) {
+  const core = await create(t)
+  const atom = core.state.storage.createAtom()
+  const atomic = core.session({ atom })
+
+  await atomic.ready()
+
+  const snap = core.snapshot()
+  await snap.ready()
+
+  t.is(snap.length, 0, 'snapshot opened successfully')
+
+  await snap.close()
+  await atomic.close()
+})